/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.cep.nfa;

import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.cep.Event;
import org.apache.flink.cep.nfa.aftermatch.AfterMatchSkipStrategy;
import org.apache.flink.cep.nfa.sharedbuffer.SharedBuffer;
import org.apache.flink.cep.nfa.sharedbuffer.SharedBufferAccessor;
import org.apache.flink.cep.pattern.Pattern;
import org.apache.flink.cep.pattern.conditions.IterativeCondition;
import org.apache.flink.cep.pattern.conditions.SimpleCondition;
import org.apache.flink.cep.time.TimerService;
import org.apache.flink.cep.utils.TestSharedBuffer;
import org.apache.flink.cep.utils.TestTimerService;
import org.apache.flink.streaming.api.windowing.time.Time;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.util.Collection;
import java.util.List;
import java.util.Map;

import static org.apache.flink.cep.utils.NFAUtils.compile;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

/**
 * Tests if the {@link NFAState} status is changed after processing events.
 */
public class NFAStatusChangeITCase {

	private SharedBuffer<Event> sharedBuffer;
	private SharedBufferAccessor<Event> sharedBufferAccessor;
	private AfterMatchSkipStrategy skipStrategy = AfterMatchSkipStrategy.noSkip();
	private TimerService timerService = new TestTimerService();

	@Before
	public void init() {
		this.sharedBuffer = TestSharedBuffer.createTestBuffer(Event.createTypeSerializer());
		sharedBufferAccessor = sharedBuffer.getAccessor();
	}

	@After
	public void clear() throws Exception{
		sharedBufferAccessor.close();
	}

	@Test
	public void testNFAChange() throws Exception {
		Pattern<Event, ?> pattern = Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 1858562682635302605L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("a");
			}
		}).followedByAny("middle").where(new IterativeCondition<Event>() {
			private static final long serialVersionUID = 8061969839441121955L;

			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				return value.getName().equals("b");
			}
		}).oneOrMore().optional().allowCombinations().followedBy("middle2").where(new IterativeCondition<Event>() {
			private static final long serialVersionUID = 8061969839441121955L;

			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				return value.getName().equals("d");
			}
		}).followedBy("end").where(new IterativeCondition<Event>() {
			private static final long serialVersionUID = 8061969839441121955L;

			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				return value.getName().equals("e");
			}
		}).within(Time.milliseconds(10));

		NFA<Event> nfa = compile(pattern, true);

		NFAState nfaState = nfa.createInitialNFAState();

		nfa.process(sharedBufferAccessor, nfaState, new Event(1, "b", 1.0), 1L, skipStrategy, timerService);
		assertFalse("NFA status should not change as the event does not match the take condition of the 'start' state", nfaState.isStateChanged());

		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(2, "a", 1.0), 2L, skipStrategy, timerService);
		assertTrue("NFA status should change as the event matches the take condition of the 'start' state", nfaState.isStateChanged());

		// the status of the queue of ComputationStatus changed,
		// more than one ComputationStatus is generated by the event from some ComputationStatus
		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(3, "f", 1.0), 3L, skipStrategy, timerService);
		assertTrue("NFA status should change as the event matches the ignore condition and proceed condition of the 'middle:1' state", nfaState.isStateChanged());

		// both the queue of ComputationStatus and eventSharedBuffer have not changed
		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(4, "f", 1.0), 4L, skipStrategy, timerService);
		assertFalse("NFA status should not change as the event only matches the ignore condition of the 'middle:2' state and the target state is still 'middle:2'", nfaState.isStateChanged());

		// both the queue of ComputationStatus and eventSharedBuffer have changed
		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(5, "b", 1.0), 5L, skipStrategy, timerService);
		assertTrue("NFA status should change as the event matches the take condition of 'middle:2' state", nfaState.isStateChanged());

		// both the queue of ComputationStatus and eventSharedBuffer have changed
		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(6, "d", 1.0), 6L, skipStrategy, timerService);
		assertTrue("NFA status should change as the event matches the take condition of 'middle2' state", nfaState.isStateChanged());

		// both the queue of ComputationStatus and eventSharedBuffer have not changed
		// as the timestamp is within the window
		nfaState.resetStateChanged();
		nfa.advanceTime(sharedBufferAccessor, nfaState, 8L);
		assertFalse("NFA status should not change as the timestamp is within the window", nfaState.isStateChanged());

		// timeout ComputationStatus will be removed from the queue of ComputationStatus and timeout event will
		// be removed from eventSharedBuffer as the timeout happens
		nfaState.resetStateChanged();
		Collection<Tuple2<Map<String, List<Event>>, Long>> timeoutResults = nfa.advanceTime(sharedBufferAccessor, nfaState, 12L);
		assertTrue("NFA status should change as timeout happens", nfaState.isStateChanged() && !timeoutResults.isEmpty());
	}

	@Test
	public void testNFAChangedOnOneNewComputationState() throws Exception {
		Pattern<Event, ?> pattern = Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("start");
			}
		}).followedBy("a*").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 1858562682635302605L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("a");
			}
		}).oneOrMore().optional().next("end").where(new IterativeCondition<Event>() {
			private static final long serialVersionUID = 8061969839441121955L;

			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				return value.getName().equals("b");
			}
		}).within(Time.milliseconds(10));

		NFA<Event> nfa = compile(pattern,  true);

		NFAState nfaState = nfa.createInitialNFAState();

		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(6, "start", 1.0), 6L, skipStrategy, timerService);

		nfaState.resetStateChanged();
		nfa.process(sharedBufferAccessor, nfaState, new Event(6, "a", 1.0), 7L, skipStrategy, timerService);
		assertTrue(nfaState.isStateChanged());
	}

	@Test
	public void testNFAChangedOnTimeoutWithoutPrune() throws Exception {
		Pattern<Event, ?> pattern = Pattern.<Event>begin("start").where(new IterativeCondition<Event>() {
			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				return value.getName().equals("start");
			}
		}).followedBy("end").where(new IterativeCondition<Event>() {
			private static final long serialVersionUID = 8061969839441121955L;

			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				return value.getName().equals("end");
			}
		}).within(Time.milliseconds(10));

		NFA<Event> nfa = compile(pattern,  true);

		NFAState nfaState = nfa.createInitialNFAState();

		nfaState.resetStateChanged();
		nfa.advanceTime(sharedBufferAccessor, nfaState, 6L);
		nfa.process(sharedBufferAccessor, nfaState, new Event(6, "start", 1.0), 6L, skipStrategy, timerService);

		nfaState.resetStateChanged();
		nfa.advanceTime(sharedBufferAccessor, nfaState, 17L);
		assertTrue(nfaState.isStateChanged());
	}
}
